Plasticizers are incorporated into a resin (usually a polymer or elastomer) to increase the flexibility, workability, or distensibility of the resin. The largest use of plasticizers is in the production of “plasticized” or flexible polyvinyl chloride (PVC) products. Typical uses of plasticized PVC include films, sheets, tubing, coated fabrics, wire and cable insulation and jacketing, flooring materials such as vinyl sheet flooring or vinyl floor tiles, adhesives, sealants, inks, and medical products such as blood bags and tubing, and the like.
Other polymer systems that use plasticizers include polyvinyl butyral, acrylic polymers, poly(vinyldiene chloride), nylon, polyolefins, and certain fluoroplastics. Plasticizers can also be used with rubber (although often these materials are referred to as “extenders” for rubber rather than plasticizers). A listing of the major plasticizers and their compatibilities with different polymer systems is provided in “Plasticizers,” A. D. Godwin, in Applied Polymer Science 21st Century, edited by C. D. Craver and C. E. Carraher, Elsevier (2000); pp. 157-175.
Plasticizers can be characterized on the basis of their chemical structure. The most important chemical class of plasticizers is phthalic acid esters, which accounted for about 85% worldwide of PVC plasticizer usage in 2002. For various reasons, particularly a combination of environmental and regulatory pressures, there is a movement away from using phthalates as plasticizers.
Two other important chemical classes are adipic acid esters, and trimellitic acid esters. These are currently expensive to produce and are not available in sufficient quantity to replace phthalates plasticizers. Newer plasticizers, such as esters based on cyclohexanoates (mono-, di-, and tri-acid esters) and benzoic acid are now commercially available but have not yet been shown to be generally useful in replacing phthalates in polymer systems such as PVC.
The concept of using polyketone materials as plasticizers for PVC has been described, for instance, in U.S. Pat. No. 6,750,278. Polyketone materials prepared with multicomponent feeds have been described inter alia in U.S. Pat. Nos. 6,541,586; 6,740,718; and 6,642,328. See also U.S. Pat. Nos. 6,156,872; 6,262,225; 6,777,514; 6,864,319; and 6,881,806.
There are numerous problems encountered in making commercial products using the aforementioned plasticizers. The problem areas include plasticizer color, plasticizer odor, and with the physical properties of the final composition and articles made therefrom, such as viscosity, haze, heat stability, UV stability, volatility, permanence, exudation, low temperature flexibility, and plasticizer efficiency.
The present inventors have surprisingly discovered novel polyketone oligomers, such as ethylene-butene-carbon monoxide oligomers, that provide improvement over heretofore available polyketone compounds in several areas, including, their use as plasticizers.